It is generally desirable to maximize the combustion gas temperature of a gas turbine engine, consistent with turbine and nozzle integrity, to maximize efficiency of the engine. State of the art metal turbine wheels permit a turbine inlet temperature of approximately 2000.degree. F. Any significant increase in this temperature requires use of alternate materials, for example, ceramics or carbon. While the maximum useful service temperature of coated carbon is approximately 6000.degree. F., absolute strength of this material is well below requirements unless reinforced. On the other hand, filament or fiber forms of carbon, exhibit relatively high tensile strength. Thus, a solution to the low strength problem of carbon is to weave or orientate carbon fibers into a laminate.
One problem associated with the manufacture of composite turbine wheels is that of orienting the carbon fibers so that they will carry most of the centrifugal and thermal stresses generated in the bladed turbine wheel. It is desirable to have a radial orientation of the fibers in the blade area of the wheel because of the nature of the stresses. However, in the hub area, a circumferential orientation of the fibers is preferable. While it is known to manufacture the blades of compressor rotors as a composite structure utilizing fiberglass reinforced plastic, and it is known to use a combination of amorphous carbon plus carbon filaments in products such as aircraft brake discs and re-entry heat shields, it remains a problem to properly orientate the reinforcing filaments of such composite material in the turbine wheel application.